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The Hudson Primer

The Hudson Primer: The Ecology of an Iconic River

David L. Strayer
Copyright Date: 2012
Edition: 1
Pages: 224
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  • Book Info
    The Hudson Primer
    Book Description:

    This succinct book gives an intimate view of the day-to-day functioning of a remarkable river that has figured prominently in history and culture—the Hudson, a main artery connecting New York, America, and the world. Writing for a wide audience, David Strayer distills the large body of scientific information about the river into a non-technical overview of its ecology. Strayer describes the geography and geology of the Hudson and its basin, the properties of water and its movements in the river, water chemistry, and the river’s plants and animals. He then takes a more detailed look at the Hudson’s ecosystems and each of its major habitats. Strayer also discusses important management challenges facing the river today, including pollution, habitat destruction, overfishing, invasive species, and ecological restoration.

    eISBN: 978-0-520-95239-3
    Subjects: Ecology & Evolutionary Biology

Table of Contents

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  1. Front Matter
    (pp. i-vi)
  2. Table of Contents
    (pp. vii-viii)
    (pp. ix-x)
  4. Introduction
    (pp. 1-10)

    The purpose of this primer is to provide a brief, nontechnical introduction to the ecology of the Hudson River estuary. The Hudson is one of the world’s most beloved, closely studied, and heavily used rivers. Because the river has been so intensively studied, a great deal is known about its physical structure, the pattern of water flows, the chemical content of its water and sediments (including many human-made contaminants), and its plants, animals, and bacteria. Unfortunately, much of this information is contained in highly technical papers and reports that would be hard for anyone other than a trained scientist to...

  5. CHAPTER ONE The Physical Character of the Hudson and Its Watershed
    (pp. 11-24)

    The physical structure of a river and the surrounding landscape sets much of the ecological character of the river. Whether the river is wide or narrow, deep or shallow, steep or sluggish; whether it is open to the ocean, partly protected, or altogether cut off from the sea; whether it has strong or weak tides, much freshwater flow or little—all of these factors together determine what species will survive, what ecological processes will predominate, and what impacts human activities will have on that river. Likewise, factors such as the depth and chemistry of soils in the watershed, and whether...

  6. CHAPTER TWO Water, Circulation, and Salinity in the Hudson River
    (pp. 25-42)

    Water is an unusual substance with many special properties that affect the ecological functioning of the Hudson. The following are a few properties of water that are especially important ecologically.

    Many substances dissolve in water, especially if they are electrically charged (what a chemist would call “polar”). Thus most simple salts—like ordinary table salt (sodium chloride) and limestone (calcium carbonate)—are very soluble in water.* Most common gases (like nitrogen and oxygen) are only a little soluble in water, and so exist in nature in the low mg/L range. Gas solubility falls with rising temperature, so warm water can...

  7. CHAPTER THREE A Brief Introduction to the Hudson’s Water Chemistry
    (pp. 43-57)

    Why would anyone but a chemist be interested in water chemistry? In the introduction I made the claim that physics, chemistry, and biology are tightly linked in ecosystems. In particular, the biology that many of you are interested in is closely tied to water chemistry, in two ways. First, water chemistry determines the suitability of a habitat for aquatic organisms. Thus phytoplankton need to be able to take up nutrients such as phosphorus and nitrogen from the water, and fish breathe by taking up the oxygen that is dissolved in the water. If the water contains too little phosphorus, nitrogen,...

  8. CHAPTER FOUR Habitats, Biological Communities, and Biota
    (pp. 58-74)

    Aquatic ecologists have developed an elaborate terminology to describe underwater habitats. I will introduce just a handful of these terms, which we will need later (see fig. 15). The zone at the shoreline that is submerged during high tide but exposed to the air during low tide is theintertidal zone. Below this is thesubtidal zone, which is always submerged. The area near the shoreline that is shallow enough to support rooted plants is called thelittoral zone. The littoral zone includes the entire intertidal zone, as well as parts of the subtidal zone. The open water beyond the...

  9. CHAPTER FIVE Ecology of the Major Habitats in the Hudson River: The Freshwater Channel
    (pp. 75-90)

    In the next few chapters, we will consider the ecology of the major habitats in the Hudson: the freshwater channel, the brackish-water channel, the vegetated shallows, and wetlands. Together, these four habitats account for most of the estuary, and have been well studied by ecologists. Other habitats, such as shorelines, tributary mouths, and sand- and mudflats, also occur in the river and may be ecologically important, but are of smaller extent and have not been as well studied.

    Although we will consider each habitat separately, we must always remember that these habitats are connected to one another, and together function...

  10. CHAPTER SIX The Brackish-Water Channel
    (pp. 91-107)

    The brackish channel is the second major habitat of the Hudson, covering all areas downriver from about West Point (RKM 85) where the water is too deep to support rooted vegetation. At least a little sea salt is often present in this part of the Hudson. Because rooted vegetation is scarce everywhere in the lower estuary, this habitat covers nearly the whole area of the river south of West Point. (Rooted plants probably are absent from much of the shallows in Haverstraw Bay and the Tappan Zee because the water is more turbid than in the freshwater Hudson, the salinity...

  11. CHAPTER SEVEN The Vegetated Shallows
    (pp. 108-120)

    Physically, chemically, and biologically, the vegetated shallows habitat is vastly different from the open channel habitats we’ve discussed so far. The vegetated shallows includes subtidal areas shallow enough—no more than 3 meters (10 feet) deep at mean water level—to support rooted plants. Much of this habitat is only waist deep (1 meter) at low tide. This habitat is structurally complex—when you snorkel through a bed of wild celery, you literally can’t see your outstretched hand through the dense canopy of leaves. Because of this combination of structural complexity and shallowness (which allows sunlight to reach all the...

  12. CHAPTER EIGHT Wetlands
    (pp. 121-134)

    Wetlands are the fourth major habitat in the Hudson. By “wetlands,” I mean areas usually lying in the intertidal zone (between mean low water and mean high water) and dominated by emergent plants like cattails, reeds, and cordgrass or by swamp trees. These wetlands sometimes are divided into “marshes,” dominated by herbaceous plants, and “swamps,” where woody trees and shrubs predominate.

    Typically, wetlands lie between beds of wild celery or water chestnut on the river side and upland forests or other vegetation on the land side. Wetlands occur in the Hudson both as thin fringes along many shorelines and as...

  13. CHAPTER NINE PCBs and Other Pollution in the Hudson
    (pp. 135-147)

    The Hudson’s watershed was settled by Europeans nearly 400 years ago and now contains about four million people. The river itself has been heavily used for transportation, waste disposal, and as a source of natural resources for centuries, often without serious consideration of the ecological consequences of these activities. Therefore, the modern Hudson is far from pristine. In the next few chapters, we will examine some of the larger human impacts on the ecology of the Hudson.

    Although it may seem to you that the Hudson in particular has been especially battered by human activity, some or all of the...

  14. CHAPTER TEN Habitat Change and Restoration in the Hudson
    (pp. 148-159)

    One of the most important ways that humans have changed the character of the Hudson River ecosystem is by physically altering the habitats in and around the river. Several kinds of physical change have had broad ecological effects.

    Probably the most important physical changes to habitats in the Hudson resulted from dredging and filling to make the river channel better for commercial navigation. In its natural state, the Hudson River north of the city of Hudson (RKM 188) contained multiple channels and islands and lots of shallow water (see fig. 35). As interesting as such a river may be to...

  15. CHAPTER ELEVEN Hudson River Fisheries
    (pp. 160-172)

    Some changes to biological populations in the Hudson were caused directly by human activities. This chapter focuses on the fisheries of the Hudson and their possible impacts on the river’s ecosystem, and the next chapter discusses the movement of nonnative species into the Hudson basin.

    Harvesting of aquatic animals has been one of the most important human uses of the Hudson (and other aquatic ecosystems) over the past few thousand years. Particularly since about 1800, harvests of fish and shellfish from the Hudson have been large enough to affect populations of the target species, and possibly extend to other parts...

  16. CHAPTER TWELVE Nonnative Species and Their Ecological Effects
    (pp. 173-192)

    At the same time that overfishing and habitat change were diminishing populations of native species, humans were bringing species from other parts of the world into the Hudson basin. Many of these nonnative species prospered and had large ecological effects on the Hudson. Invasion biologists have not settled on a consistent terminology for these species, so the species that I call “nonnative” other ecologists call alien, exotic, nonindigenous, introduced, or invasive—terms that have similar (but not exactly the same) meanings. (This chapter is based on Strayer 2006.)

    Nonnative species include both species that were introduced deliberately by people (brown...

  17. Conclusion: A Few Parting Thoughts
    (pp. 193-198)

    I have found that talking about the current ecological condition of the Hudson River depresses audiences, and I don’t think it’s just my lecture style. If you have made it this far, you may likewise be depressed about the condition of the Hudson and pessimistic about its future.

    There is indeed much to be depressed about. Humans destroyed huge areas of productive shallows and shoreline, drove populations of commercially valuable species down to the point of ecological irrelevance, brought in more than a hundred nonnative species, stripped forests from the watershed, and turned the river into a Superfund site that...

  18. INDEX
    (pp. 199-207)
  19. Back Matter
    (pp. 208-208)